Pressurized spray canisters have long been utilized as economical, convenient, and portable storing and dispensing devices, accommodating products as diverse as paint, insecticide, whipped cream, etc. Because of the pressurized spray canister's wide spread popularity and applicability, millions and millions of units are manufactured each year throughout the world. Improvements in the design and manufacturing processes are constantly sought after by the spray canister industry, since even a very minor cost reduction per unit, given even one manufacturer's production volume, can quickly accumulate into large production savings.
Pressurized spray canisters typically have a cylindrical metal container or canister sealed by a mounting cup and valve assembly combination. Alternatively, a metal pressure dome may seal the a wider open end of the canister, with the mounting cup and valve assembly, in turn, being sealingly engaged with a central opening of the pressure dome. This causes a valve stem and spray button portion of the valve assembly to be disposed a greater distance away from a top surface of the canister, which facilitates more accurate and easy product dispensing.
Two types of valve assemblies are typically provided with pressurized spray canisters. One is a vertical depression-valve assembly, where product is dispensed when the valve stem is vertically depressed along the vertical axis of the valve. The other is a tilt-valve assembly, where product is dispensed when the valve stem is sufficiently tilted from the vertical axis of the valve. The former is most often used in conjunction with right-angle spray buttons and actuators for spraying product radially with respect to the canister, and the later is most often used with spray-through spray buttons and actuators for providing off-axis dispensing.
Spray canister mounting cups, for use with tilt-valve assemblies for example, typically have an exterior, outwardly facing surface and an interior, inwardly facing surface, a perimeter curl for attaching or securing the mounting cup to the rim of the canister or dome, and a centrally located aperture surrounded by a generally flat-top surface of the pedestal portion. The pedestal portion serves to partially house the valve assembly and also assists with positioning the valve stem and spray button a small distance away from the top of the canister.
Known tilt-valve assemblies have a washer-shaped gasket disposed within the interior of the pedestal portion, about the centrally located aperture, to form a first portion of a seal. An internal area of a valve body supports a compression spring, which biases a base of the valve stem against the gasket to form the second component of the seal and achieve an adequate seal between the interior of the canister and the exterior environment. The valve stem has a product outlet which communications with at least one and preferably a plurality of radially extending orifices that are located just below the gasket but above the base of the valve stem.
During use, once the valve stem is sufficiently tilted, e.g. causing one side portion of the valve stem base to "bite into the gasket" while the opposite side portion of the valve stem base to be sufficiently lifted away from the gasket, the flow of the product to be dispensed from the canister is allowed through the valve. The product to be dispensed then communicates with the one or more radial orifices and flows vertically upward, along the passageway in the valve stem, and out through a discharge outlet of a spray button or actuator, in a conventional fashion.
Turning now to FIG. 1, a brief description concerning one prior art mounting cup and tilt-valve assembly arrangement will be provided. As can be seen in this figure, the valve assembly is accommodated within the pedestal portion 28 of the mounting cup 10 in a conventional manner. By this arrangement, the gasket 32 and the top wall 30 of the pedestal portion 28 are both substantially planar and extend substantially parallel to one another. Due to this arrangement, the circumferential sealing protrusion 60 which engages with the gasket 32 is much more pronounced and forms a fairly deep annular well 55 between the circumferential sealing protrusion 60 and the central region of the valve stem 52. This arrangement leads to a more complicated valve stem 52 in which the radial orifices 64 can not be readily molded in the valve stem during a single manufacturing step, e.g. a subsequent manufacturing step is required to form the radial orifice or radial orifices 64.
The disadvantage of the above referenced prior art design is that the radial orifice or orifices generally have a relatively small diameter in order to be located between the base of the valve stem and an adjacent undersurface surface of the gasket. This is because there is only a very small clearance or area between the undersurface surface of the gasket and the adjacent top surface of the valve stem base. With a planar gasket, it is extremely difficult to provide both a proper seal between the valve stem base and gasket and a sufficient clearance for relatively large radial orifices.
Such tiny radial orifices are often only pin-hole sized, having a diameter of around 0.013 inches or so. Because of the required position of the holes, it is extremely difficult to accurately form the holes in the valve stem, especially during commercial production, as part of the initial molding process, and a further orifice forming step is required. Thus, not only must an extra manufacturing step be carried out for each valve stem, but the orifice forming equipment is expensive to purchase, maintain and operate and, because the radial orifices must be accurately positioned, sometimes the orifice forming equipment requires adjustment. Such expenses and/or adjustment delays can greatly slow down production speed and increase production costs.
Also, as the pin-hole sized radial orifices provide a minimal cross-sectional product flow path, the ability to supply the product to be dispensed, via a conventional through-the-valve-stem charging process, is also somewhat hindered.
Furthermore, although it is theoretically possible to provide larger diameter radial orifices 64 in the valve stem 52 (for example, dimensioned to be the same size as the well 55), such radial orifices would still have to be accurately placed and formed via at least one additional manufacturing step.